package ar.com.larctest.utils;

import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class MCrypt {

    private IvParameterSpec ivspec;
	private SecretKeySpec keyspec;
	private Cipher cipher;

	protected String SecretKey;//Dummy secretKey (CHANGE IT!)

	public MCrypt()
	{
        String iv = "#EDC4rfvf2d2r3c4";
        ivspec = new IvParameterSpec(iv.getBytes());

        SecretKey = "f2d2r3c4#EDC4rfv";
        keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");

		try {
			cipher = Cipher.getInstance("AES/CBC/NoPadding");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		}
	}

	public byte[] encrypt(String text) throws Exception
	{
		if(text == null || text.length() == 0)
			throw new Exception("Empty string");

		byte[] encrypted;

		try {
			cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);

			encrypted = cipher.doFinal(padString(text).getBytes());
		} catch (Exception e)
		{
			throw new Exception("[encrypt] " + e.getMessage());
		}

		return encrypted;
	}

    public byte[] decrypt(String code) throws Exception
    {
        if(code == null || code.length() == 0)
            throw new Exception("Empty string");


        byte[] decrypted;


        try {
            cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);


            decrypted = cipher.doFinal(hexToBytes(code));
            //Remove trailing zeroes
            if( decrypted.length > 0)
            {
                int trim = 0;
                for( int i = decrypted.length - 1; i >= 0; i-- ) if( decrypted[i] == 0 ) trim++;


                if( trim > 0 )
                {
                    byte[] newArray = new byte[decrypted.length - trim];
                    System.arraycopy(decrypted, 0, newArray, 0, decrypted.length - trim);
                    decrypted = newArray;
                }
            }
        } catch (Exception e)
        {
            throw new Exception("[decrypt] " + e.getMessage());
        }
        return decrypted;
    }

	public static String bytesToHex(byte[] data)
	{
		if (data==null)
			return null;

        String str = "";
        for (byte aData : data) {
            if ((aData & 0xFF) < 16)
                str = str + "0" + Integer.toHexString(aData & 0xFF);
            else
                str = str + Integer.toHexString(aData & 0xFF);
        }
		return str;
	}


	public static byte[] hexToBytes(String str) {
		if (str==null)
			return null;
		else if (str.length() < 2)
			return null;
		else {
			int len = str.length() / 2;
			byte[] buffer = new byte[len];
			for (int i=0; i<len; i++) {
				buffer[i] =  (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
            }
			return buffer;
		}
	}

	private static String padString(String source)
	{
	  char paddingChar = ' ';
	  int size = 16;
	  int x = source.length() % size;
	  int padLength = size - x;

	  for (int i = 0; i < padLength; i++)
		  source += paddingChar;

	  return source;
	}
}